Select2 - Select2 offers customizable select box with support for searching, tagging, infinite scrolling, and many other used options.
PayPal - PayPal is the faster, safer way to pay online without sharing financial details, send and receive money or accept credit and debit cards as a seller
Bootstrap - Simple and flexible HTML, CSS, and JS for popular UI components and interactions
Stripe - Online payment processing for internet businesses. Stripe is a suite of payment APIs that powers commerce for online businesses of all sizes. Use Stripe’s payment platform to accept and process payments online for easy-to-use commerce solutions.
Material UI - A CSS Framework and a Set of React Components that Implement Google's Material Design
Braintree - An all-in-one solution to accept, process, and split payments in your mobile app or online - from small business to large enterprise.